Abstract

High speed lasers are key components for wide-band optical-fiber communication systems. In this paper we report on the performance of compressively strained (CS) multiple-quantum-well (MQW) In-GaAsP / InP distributed-feedback (DFB) lasers operating at a 1.3-μm wavelength. The lasers were fabricated by a two-step hybrid crystal-growth technique. The 1%-CS 10-QW separate-confinement heterostructures (SCH) were prepared by low-pressure metal-organic chemical-vapor deposition (MOCVD). The width of each well was 34Å, and the width of each SCH layer was 500 A (Fig. 1). The well width, the number of wells, and the width of the SCH layer were designed for high-speed operation.^1-4 The SCH-layer thickness of 500 Å, which is less than the commonly used 2000 Å, reduced the state-filling, or carrier-transport, effect.^3,4 After MOCVD growth, mesas with widths of approximately 1.5 μm were etched, followed by buried-heterostructure (BH) blocking-layer growth. Parasitic capacitance was minimized by etching narrow mesas (7 μm) around the active stripe, and air bridges were fabricated across the isolation channel to connect the laser contact and bonding pad.⁵ The lasers were asymmetrically (AR/HR) coated for single-mode operation. Additional differential-gain enhancement was obtained by detuning the Bragg wavelength by −150 Å from the threshold gain peak.

© 1995 Optical Society of America